Method and apparatus for adjusting sweep-out frequency for an imaging apparatus responsive to an operating state of a strobo means

ABSTRACT

An operating condition judging means judges at least one of consumed current, whether or not a mechanically driven part is being operated, the supply voltage level, the ambient temperature, whether or not the lens stop means is operative, whether or not the strobo means is being charged, and whether or not access operation of recording means is being performed. A control means controls a frequency of sweep-out of unnecessary charge in the imaging element on the basis of the output of the operating condition judging means. Thus, it is possible to effectively reduce the peak consumed current through the entire imaging apparatus, reduce the power consumption and extend the battery life.

BACKGROUND OF THE INVENTION

[0001] The present invention relates to imaging apparatus having animaging element, which are used for electronic still cameras, digitalcameras and the like.

[0002] Hitherto, various imaging elements applicable to such imagingapparatuses have been proposed. Among such imaging elements is aninter-line CCD solid-state imaging element having a vertical overflowdrain structure as schematically shown in FIG. 15.

[0003] The CCD shown in FIG. 15 comprises a two-dimensional array ofphoto-diodes 1 arranged in both horizontal and vertical directions andeach constituting a photo-electric converting cell or accumulatingcharge according to light incidence, a plurality of vertical shiftregisters 3 constituting vertical shift paths for receiving chargeaccumulated in associated photo-diodes 1 via a transfer gate 2 andprogressively vertically shifting the received charge, a horizontalshift register 4 constituting a horizontal shift path for receivingshifted charge from the vertical shift registers 3 and progressivelyhorizontally shifting the received charge, and a signal detector 5 foramplifying the output signal of the horizontal shift register 4 andoutputting the amplified signal.

[0004]FIG. 16 is a block diagram showing the basic construction of animaging apparatus with the CCD shown in FIG. 15. The illustrated imagingapparatus comprises a focusing lens 11, a shutter means 12, a CCD 13, asignal processor 14, a shutter driver 16, a signal generator 17, a CPU18, a lens stop means 20, a recording means 21 and a lens stop driver22. The focusing lens 11 focuses a light beam of a scene on a lightincidence surface of the CCD 13. The lens stop means 20 stops or reducesthe area of the light flux of the scene from the lens 11. The shuttermeans 12 is constituted by, for instance, a mechanical shutter foreither passing or blocking the scene light flux. The CCD 1 converts thescene light beam flux having passed through the shutter means 12 to anelectric signal. The signal processor 14 performs various processes onthe electric signal from the CCD 13 and outputs an image signal thusgenerated. The recording means 21 has a DRAM for storing the imagesignal from the signal processor 14 as a still image or a recordingmedium on which the compresses image signal is recorded as a stillimage. The shutter driver 16 controls the shutter means 12. The lensstop driver 22 controls the lens stop means 20. The signal generator 17supplies pulses for controlling the period of charge accumulation in thephoto-diodes 1, pulses for driving the vertical shift registers 3 andpulses for driving the horizontal shift register 4 to the CCD 13 andalso supplies pulses for driving the signal processor 14 in synchronismto the CCD 13. The CPU 18 collectively controls circuits including thesignal generator 17 and the lens stop driver 22. The signal processor 14and the signal generator 17 together constitute a digital signalprocessor (DSP) 19.

[0005]FIG. 17 is a timing chart illustrating a conventional imagingoperation in the imaging apparatus shown in FIG. 16. Specifically, theFigure shows a vertical sync signal VD, a transfer gate pulse train TG,a sub-pulse train SUB, a vertical shift register shift pulse train VT, aclamp pulse train CLP, opening/closing operation of the shutter means12, operations of the lens stop means 20 and the lens stop driver means22 and a CCD signal, i.e., a signal read out from the CCD 13.

[0006] The vertical sync signal VD is a pulse train prescribing apredetermined unit period of time for obtaining signal representing oneimage (i.e., one frame image). Here, periods prescribed by theindividual pulses are labeled V1, V2, . . . .

[0007] The transfer gate pulse train TG consists of pulses fordetermining the timing of the transfer of charge stored in thephoto-diodes 1 to the vertical shift registers 3, and is applied to thetransfer gate 2 in synchronism to the vertical sync signal VC. Thetransfer gate pulses TG corresponding to the periods V1, V2, . . . ofthe vertical sync signal VD are labeled TG0, TG1, . . . .

[0008] The sub-pulse train SUB consists of pulses for discharging chargegenerated in the photo-diodes 1 in the vertical direction of thesubstrate. The charge discharge is done while sub-pulses SUB areoutputted. That is, the charge is accumulated in the photo-diodes 1during periods tb1, tb2, . . . , in which the sub-pulses SUB are stoppedin the periods V1, V2, . . . of the vertical sync signal VD. Thus, itwill be seen that a so-called electron (or element) shutter is realized,in which the effective exposure time is controlled through control ofthe charge accumulation period. The charge accumulation time isdetermined as a result of measurement of light of the scene image with ameasuring means (not shown), and it is measured by counting sub-pulsesSUB.

[0009] The vertical shift register shift pulse train VT consists ofpulses for causing progressive shift of charge in the vertical shiftregisters 3 toward the horizontal shift register 4.

[0010] The clamp pulse train CLP consists of pulses for clampingportions of the CCD signal corresponding to optical black portion of theCCD. By the clamping, the potential level of the image signal isstabilized to hold a stable black level.

[0011] The shutter means 12 is normally open, and is closed(light-shuttered or -blocked) when causing the transfer of chargeaccumulated in the photo-diodes 1 in response to a recording triggersignal. As the recording trigger signal, in the case of a shutterrelease button (not shown) providing a two-stage trigger signal, thatis, in the case when a first trigger pulse is generated in a preparatorystage of lightly depressing the shutter release button for recording anda second trigger pulse is generated by further depressing the shutterrelease button for starting the recording of a still image, the secondtrigger pulse corresponds to the recording trigger signal.

[0012] The CCD signal has time sections to1 and to2 corresponding tooptical black portions in the vertical direction and an effective timesection intervening as a scene image period between these time sections.Normally the optical black signal is at a higher level than theeffective period signal level.

[0013] The lens stop means 20 is normally in an open diameter state, inthe case of such a bright scene that normal exposure will be exceededwith the sole electronic shutter operation in its open diameter state,it is driven to stop the light flux.

[0014] As is seen from the timing chart of FIG. 17, in the prior artimaging apparatus upon generation of a recording trigger signal in, forinstance, the period V3, vertical shift register shift pulses VT arecontinuously outputted during a subsequent time section ta for fastsweep-out of unnecessary charge in the vertical shift registers 3, whilesteadily applying shift pulses without any pause period for theread-out. In the subsequent period V4, the charge is accumulated in thephoto-diodes 1 by suspending the application of sub-pulses SUB for atime section tb4 corresponding to the exposure period, which has beendetermined by a light measurement process executed on the basis of theCCD signal until the recording trigger signal generation. At this time,appropriate exposure may not be ensured with the sole electronic shutteroperation. In such a case, in synchronism to the start of the period V4the lens stop driver 22 is turned on to cause the lens stop means 20 tostop or decrease the diameter of the scene light flux. At any rate, thetime section tb4 constitutes an exposure time for one frame image.

[0015] In the subsequent period V5, the image obtained by the exposureduring the time section tb4 in the period V4 is outputted as signalCCD4, which is outputted as a result of the exposure in response to therecording trigger signal from the signal amplifier 5. Also, insynchronism to the start of the period V5 the lens stop means 20 isdriven back to the open state, while the shutter driver 16 is caused todrive the shutter means 12 for closing. In the subsequent period V6, theshutter means 12 is opened. The image obtained by exposure as a resultof the closing operation of the shutter means 12 in the period V5, isoutputted as signal CCD5 in the subsequent period V5. Since the signalCCD5 is obtained while the shutter means is blocking incident light, thesignal levels in the optical black portion time sections and theeffective period are substantially equal.

[0016] As shown above, in the prior art imaging apparatus, fastsweep-out of charge from the vertical shift registers 3 is executed inthe period V3, during which the recording trigger signal is generated,the lens stop means 20 is selectively operated while causing chargeaccumulation in the photo-diodes 1 during the time section tb4 in thesubsequent period V4, the lens stop means 20 is opened while driving theshutter means 12 for closing to cause transfer of the accumulated chargein the subsequent period V5, and the shutter means 12 is opened again inthe subsequent period V6.

[0017] In the above prior art imaging apparatus, however, a responsetime tm is required from the start of the closing operation of theshutter means 12 until the perfectly closed state is brought about. Inother words, even with the closing operation started at the start of thecharge transfer period V5, during the response time tm the light isincident on the CCD 13, resulting in charge generation in thephoto-diodes 1. Therefore, particularly in case of a bright scene thecharge generated during the response time tm partly enters the verticalshift registers 3 in spite of the charge sweep-out in the verticaldirection with sub-pulses SUB. Also, the generated charge remains on thesubstrate part of the photo-diodes 1, and is shifted by the verticalshift registers 3 after the shutter means 12 has been perfectly closed.Thus, a problem of the superimposition of smear on the intrinsic CCDsignal is posed. Here, the lens stop means 20 has a responsecharacteristic similar to that of the shutter means 12.

[0018] To solve the problem noted above, the applicant has earlierproposed an imaging apparatus, which has the structure as shown in FIG.16, and in which the imaging operation is controlled with timings asshown in FIG. 18 (Japanese Patent Application No. 8-344052). In thisimaging apparatus, after the recording trigger pulse generation the fastsweep-out of unnecessary charge in the vertical shift registers 3 isexecuted in a time section tc in synchronism to transfer gate pulse TG3synchronized to the vertical sync signal VD. The vertical shift registershift pulse VT for the fast sweep-out period tc need not be synchronizedto the horizontal blanking period because of the fact that unnecessarycharge which is not used as data is swept out.

[0019] Transfer gate pulse TG4 prescribes the end instant of the fastsweep-out period tc, and also causes transfer of signal charge havingbeen accumulated during the charge accumulation time section tb4 to thevertical shift registers 3. The timing of generation of the pulse TG4 isset such that it is earlier than the start of the next period V5 by apredetermined time interval tv, which is determined on the basis of theresponse time tm of the shutter means 12 and an allowance thereof. Theshutter driver 16 is thus caused to drive the shutter means 12 forclosing in synchronism to the transfer gate pulse TG4.

[0020] Furthermore, the vertical shift of the signal charge transferredto the vertical shift registers 3, is suspended for predetermined timetv, and the read-out is started by starting the application of verticalshift register shift pulses VT in synchronism with the end of thisvertical shift suspension time tv, i.e., with the start of the nextperiod V5. The timing of the start of the charge accumulation timesection tb4 after the generation of the recording trigger signal, isdetermined to be earlier than the timing of generation of the transfergate pulse TG4 by the charge accumulation time section tb4. In the caseof determining the charge accumulation time section tb4 while causingstopping of the scene light flux, the lens stop driver 22 is turned offsuch that the lens stopping operation of the lens stop means 20 iscaused at the start of the period V4 and turned off in synchronism tothe end of the charge accumulation time section tb4, i.e., the transfergate pulse TG4.

[0021] With the imaging apparatus as described, the shutter means 12 canbe in the perfectly closed or light-blocked state in the period V5, inwhich the signal charge accumulated during the charge accumulation timesection tb4 in the period V4 is read out. It is thus possible to solvethe above problem of smear and obtain high quality image signal.

[0022] However, as a result of various experimental researches andinvestigations conducted by the inventors, it was found that the aboveimaging apparatus proposed by the applicant has the following problemsto be solved. A portable imaging apparatus such as an electronic stillcamera or a digital camera uses a battery, and consumed (consumption)power reduction is particularly demanded for such imaging apparatus. Inthe imaging apparatus as described above, the period of driving the lensstop means 20 is the same as the fast sweep-out time section tc forsweeping out unnecessary charge in the CCD 13. For the fast sweep-out,transfer pulses are applied at an iteral frequency (i.e., sweep-outfrequency) f, which is usually proportional to peak consumed current Iin the CCD 13 at this time as shown in FIG. 19. That is, with increasingsweep-out frequency of the peak consumed current I is increased toincrease the consumed power.

[0023] Therefore, where the sweep-out frequency f is fixed at a highfrequency f1, a very high peak consumed current, which includes the fastsweep-out current for the fast sweep-out and a stop holding current forholding the stopping state of the lens stop means 20, flows through theentire imaging apparatus during the fast sweep-out time section tc asshown in FIG. 18. Particularly, where the lens stop means 20 is normallyopen type, a higher peak consumed current flows at the moment of thestart of the sweep-out. Such very high peak consumed current increasesthe power consumption to reduce the battery life and, depending on thebattery capacity, reduces the supply voltage, possibly resulting instoppage of the system operation.

[0024] Such a problem is also encountered in the case where an accessoperation for writing the image data from the CCD 13 is written in therecording means 21 in the fast sweep-out time section tc, and is morereadily encountered in the case where the stopping operation of the lensstop means 20 is caused concurrently with such access operation forwriting the image data in the recording means 21. Furthermore, likeproblem is encountered where the operation of the lens stop means 20 andthe fast sweep-out of unnecessary charge are performed at differenttimings as shown in FIG. 17, the residual battery capacity is less, orthe battery capacity is reduced due to a low ambient temperature.Moreover, where signal charge in some lines of the CCD 13 is read outwhile the charge in the other lines is swept out by fast sweep-out toimprove the frame rate during a period from the first trigger pulse tillthe recording trigger, like problem is encountered in the case ofcharging a strobo means or the like concurrently during this time.

SUMMARY OF THE INVENTION

[0025] The present invention was made in view of the above background,and it has an object of providing an imaging apparatus capable ofeffective reduction of the peak consumed current through the entireimaging apparatus, reduction of the power consumption and extension ofthe battery life.

[0026] According to a first aspect of the present invention, there isprovided an imaging apparatus having an imaging element for accumulatingsignal charge corresponding to an incident scene light flux in aphoto-electric converting element section comprising: a sweep-out meansfor sweeping out unnecessary charge in the imaging element; and acontrol means for controlling the frequency of a sweep-out ofunnecessary charge by the sweep-out means.

[0027] According to a second aspect of the present invention, there isprovided an imaging apparatus having an imaging element for accumulatingsignal charge corresponding to an incident scene light flux in aphoto-electric converting element section comprising: a sweep-out meansfor sweeping out unnecessary charge in the imaging element; an operatingcondition judging means for judging operating condition of the imagingapparatus; and a control means for controlling a frequency of thesweep-out of unnecessary charge by the sweep-out means on the basis ofthe output of the operating condition judging means.

[0028] The operating condition judging means judges at least one ofconsumed current, whether or not a mechanically driven part is beingoperated, the supply voltage level, the ambient temperature, whether ornot the lens stop means is operative, whether or not the strobo means isbeing charged, and whether or not access operation of recording means isbeing performed.

[0029] According to a third aspect of the present invention, there isprovided an imaging apparatus having an imaging element for accumulatingsignal charge corresponding to an incident scene light flux in aphoto-electric converting element section comprising: a sweep-out meansfor sweeping out unnecessary charge in the imaging element; an operatingcondition judging means for judging consumed current of the imagingapparatus; and a control means for controlling a frequency of thesweep-out of unnecessary charge by the sweep-out means on the basis ofthe output of the operating condition judging means such that theconsumed current will not exceed a predetermined value.

[0030] According to a fourth aspect of the present invention, there isprovided an imaging apparatus having an imaging element for accumulatingsignal charge corresponding to an incident scene light flux in aphoto-electric converting element section comprising: a sweep-out meansfor sweeping out unnecessary charge in the imaging element; an operatingcondition judging means for judging whether or not a mechanically drivenpart is being operated; and a control means for setting a lowersweep-out frequency of the sweep-out means when a mechanically drivenpart is being operated than a mechanically driven part is not beingoperated.

[0031] According to a fifth aspect of the present invention, there isprovided an imaging apparatus having an imaging element for accumulatingsignal charge corresponding to an incident scene light flux in aphoto-electric converting element section comprising: a sweep-out meansfor sweeping out unnecessary charge in the imaging element; an operatingcondition judging means for judging the supply voltage level; and acontrol means for setting a lower sweep-out frequency of the sweep-outmeans when the supply voltage level is lower than a predeterminedvoltage.

[0032] According to a sixth aspect of the present invention, there isprovided an imaging apparatus having an imaging element for accumulatingsignal charge corresponding to an incident scene light flux in aphoto-electric converting element section comprising: a sweep-out meansfor sweeping out unnecessary charge in the imaging element; an operatingcondition judging means for judging the ambient temperature; and acontrol means for controlling the sweep-out frequency of the sweep-outmeans on the basis of the result of judgment of the ambient temperatureby the operating condition judging mean such as to reduce the sweep-outfrequency when the ambient temperature is lower than a predeterminedtemperature.

[0033] The operating condition judging means for judging the ambienttemperature is provided around the lens stop means or the power supply.

[0034] According to a seventh aspect of the present invention, there isprovided an imaging apparatus having an imaging element for accumulatingsignal charge corresponding to an incident scene light flux in aphoto-electric converting element section comprising: a lens stop meansfor stopping a light flux incident on the imaging element; a sweep-outmeans for sweeping out unnecessary charge in the imaging element; and acontrol means for controlling the sweep-out frequency of the sweep-outmeans such as to provide a lower sweep-out frequency when the lens stopmeans is operative than when the lens stop means is inoperative.

[0035] The control means reduces the sweep-out frequency of thesweep-out means when the lens stop means is operative so that theconsumed current at this time is less than the maximum consumed currentwhen the lens stop means is inoperative.

[0036] According to an eighth aspect of the present invention, there isprovided an imaging apparatus having an imaging element for accumulatingsignal charge corresponding to an incident scene light flux in aphoto-electric converting element section comprising: a strobo means forilluminating the scene incident on the imaging element; a sweep-outmeans for sweeping out unnecessary charge in the imaging element; and acontrol means for setting a lower sweep-out frequency of the sweep-outmeans when the strobo means is being charged than when the strobo meansis not being charged.

[0037] According to a ninth aspect of the present invention, there isprovided an imaging apparatus having an imaging element for accumulatingsignal charge corresponding to an incident scene light flux in aphoto-electric converting element section comprising: a recording meansfor writing image data from the imaging element; and a control means forsetting a lower sweep-out frequency of the sweep-out means during anaccess operation of the recording means to write image data than duringa non-access operation of the recording means.

[0038] According to a tenth aspect of the present invention, there isprovided an imaging apparatus having an imaging element for accumulatingsignal charge corresponding to an incident scene light flux in aphoto-electric converting element section comprising: a sweep-out meansfor sweeping out unnecessary charge in the imaging element; an operatingcondition judging means for judging predetermined plurality of operatingconditions of the imaging apparatus; and a control means for selecting afrequency of the sweep-out of unnecessary charge by the sweep-out meansamong a plurality of predetermined frequencies on the basis of thejudged operating conditions.

[0039] The plurality of frequencies is set on the basis of number of thejudged operating conditions.

[0040] Other objects and features will be clarified from the followingdescription with reference to attached drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0041]FIG. 1 shows a block diagram showing the construction of a firstembodiment of the imaging apparatus according to the present invention;

[0042]FIG. 2 shows an exploded perspective view showing an example ofthe construction of a frame unit including an optical systemconstituting the lens and the shutter means shown in FIG. 1;

[0043] FIGS. 3(a) and 3(b) show the construction of a lens stop/shutterunit 25 shown in FIG. 2;

[0044]FIGS. 4 and 5 show timing charts illustrating the imagingoperations in the first embodiment of the imaging apparatus;

[0045]FIG. 6 shows a drawing for explaining the imaging operations in asecond embodiment of the imaging apparatus;

[0046]FIG. 7 shows a flow chart for explaining the operation of thesecond embodiment of the imaging apparatus;

[0047]FIG. 8 shows a block diagram showing the construction of a thirdembodiment of the imaging apparatus according to the present invention;

[0048]FIG. 9 shows a flow chart for explaining the operation of thethird embodiment of the imaging apparatus;

[0049]FIG. 10 shows a block diagram showing the construction of a fourthembodiment of the imaging apparatus according to the present invention;

[0050]FIG. 11 shows a flow chart for explaining the operation of thefourth embodiment of the imaging apparatus;

[0051]FIG. 12 shows a block diagram showing the construction of a fifthembodiment of the imaging apparatus according to the present invention;

[0052]FIG. 13 shows a flow chart for explaining the operation of thefifth embodiment of the imaging apparatus;

[0053]FIG. 14 shows a block diagram showing a modified constructionaccording to the present invention;

[0054]FIG. 15 shows an example of CCD as the imaging element applicableto the imaging apparatus of the present invention;

[0055]FIG. 16 shows a block diagram showing the construction of a priorart imaging apparatus;

[0056]FIG. 17 shows a timing chart illustrating a conventional imagingoperation in the imaging apparatus shown in FIG. 15;

[0057]FIG. 18 shows a timing chart illustrating another conventionalimaging operation in the imaging apparatus; and

[0058]FIG. 19 shows a relationship between the sweep-out frequency ofunnecessary charge and the consumed (consumption) current.

PREFERRED EMBODIMENTS OF THE INVENTION

[0059] Preferred embodiments of the present invention will now bedescribed with reference to the drawings.

[0060]FIG. 1 is a block diagram showing a first embodiment of theimaging apparatus according to the present invention. In the Figure,parts having like functions in the imaging apparatus shown in FIG. 16are designated by like reference numerals, and their detaileddescription is not given. This imaging apparatus basically operates inthe same manner as described before in connection with the timing chartof FIG. 18. In this embodiment, however, the sweep-out frequency f forsweeping out unnecessary charge in the CCD 13 can be selectably set toeither f1 or f2 (f1>f2) in the signal generator 17. Specifically, thesignal generator 17 selectively outputs vertical shift register shiftpulses VT at the sweep-out frequency f1 or f2 under control of the CPU18 in dependence on whether or not the scene light flux is stopped bythe lens stop means 20. The lens stop means 20 and the shutter means 12are formed together to constitute a lens stop/shutter means 25.Furthermore, to the CPU 18 are connected a first release (LRSW) switch26 a, which generates a first trigger pulse in response to a first stagedepression of a shutter release button (not shown), and a second release(2RSW) switch 26 b, which generates a second trigger pulse, i.e., arecording trigger signal, in response to a second stage depression ofthe shutter release button.

[0061]FIG. 2 is an exploded perspective view showing an example of theconstruction of a frame unit including the lens stop/shutter unit 25shown in FIG. 1. Referring to the Figure, illustrated centrally is asubstantially cylindrical frame member 51 having open ends. A fixed lensframe member 52 is secured by such securing means as screwing to thefront open end of the frame member 51 on the left side (i.e., sceneside) of the Figure. A mounting base member 53 is also secured by suchsecuring means as screwing to the rear open end of the frame member 51on the right side (i.e., on the side of the CCD 13) in the Figure.

[0062] A pair of guide shafts 54 a and 54 b each have one end secured bybonding to the mounting base member 53 and the other end fittedlysupported in an edge portion of the fixed lens frame member 52, and thusextends in the frame member 51 such as to be parallel with the opticalaxis. A plurality of movable frame members 55 (such as 56G, 57G and 58G)are provided in the frame member 51 such that they can be guided fortheir sliding in the optical axis direction along the pair guide shafts54 a and 54 b.

[0063] The movable frame member 58G is movable in its state mounted on asupport 58Z and together with the movable frame members 56G and 57Galong the guide shafts 54 a and 54 b. For the sake of the brevity,optical parts with a lens are designated by reference numerals with aprefix G, and those without any lens are designated by numerals with aprefix Z. Although not exactly classified, the movable frame members 56Gand 58G are provided mainly for zooming, and the movable frame members58Z and 58G are provided for auto-focusing (AF). The movable framemembers 58Z and 58G are brought closer to or away from each other forauto-focusing by an AF motor installed on the movable frame member 58Z.

[0064] The frame member 51 has a plurality of (i.e., three in thisembodiment) ribs 51 x, 51 y and 51 z formed on its inner surface such asto extend parallel with the optical axis. The ribs 51 x, 51 y and 51 zextend from the front open end of the frame member 51 up to a positionbehind the position, at which a light flux controller for mechanicallycontrolling the light flux passing through the movable frame members 55,i.e., the lens stop/shutter unit 25, is installed. The lens stop/shutterunit 25 is accommodated into the frame member 51 from the front open endthereof; it is accommodated by causing its sliding along the ribs 51 xto 51 y with its notches formed in an edge portion of a substantiallydisc-like base member thereof in engagement with the ribs 51 a to 51 z.The ribs 51 x to 51 z each have one end formed with each of threadedholes 51 a to 51 c for securing the fixed lens frame member 52 byscrewing.

[0065] The fix lens frame member 52 has its inner periphery formed witha threaded groove 52 d to permit detachable mounting of an optical partsuch as an adapter lens or a filter from the outside. The fix lens framemember 52 has an edge portion formed with screw insertion holes 52 a to52 c, which correspond to the threaded holes 51 a to 51 c formed in thethree ribs 51 x to 51 z at one end thereof. In FIG. 2, the screwinsertion hole 52 b is concealed and not shown.

[0066] A cam assembly 62 for causing advancement and retreat of themovable frame members 55 in the optical directions, is fitted forsliding revolution on the outer periphery of the frame member 51. Thecam assembly 62 includes a first cam cylinder 62 a having an innerperipheral convex cam 63 a and a second cam cylinder 62 b coupled to thefirst cam cylinder 62 a and having an inner peripheral convex cam 63 b.The first and second cam cylinders 62 a and 62 b are integrally revolvedby the zoom motor 64 secured to the mounting substrate 53.

[0067] FIGS. 3(a) and 3(b) show the lens stop/shutter unit 25. As shown,the unit 25 includes a substantially disc-like base member 65, which isdisposed in the frame member 51 such as to be perpendicular to theoptical axis and having a central open-diameter aperture, and a lensstop member 66 and a shutter member 67 both provided in the base member.The lens stop member 65 is a thin member having a circular opening of asmaller diameter than the open diameter aperture of the base member 65.The shutter member 67 consists of two thin members. As shown in FIG.3(a), a lens stop driver 68 and a shutter driver 69 are provided on onesurface of the base member 65 such that they face each other. The stopand plunger drivers 68 and 69 both use solenoid plunger mechanisms.

[0068] As shown in FIG. 3(b), a lens stop lever 71 which is driven bythe lens stop driver 68 for driving the lens stop member 66, and ashutter lever 72 which is driven by the shutter driver 69 for drivingthe shutter 67, are provided on the other surface of the base member 65.The stop and shutter levers 71 and 72 have the same shape.

[0069] In the lens stop-shutter unit 25 having the above construction,when the lens stop driver 22 (see FIG. 1) is not driven by the lens stopdriver 68, the lens stop member 66 is concealed inside the base member65, and the central open-diameter aperture formed in the base member 65serves the role of a fix stop. When the lens stop driver 62 is driven inthis state, the lens stop lever 71 which has a portion in engagementwith a solenoid plunger core is caused to undergo revolution. As aresult, the lens stop member 66 coupled to a pin formed on the lens stoplever 71 is revolved to stop a part of the light flux through itscircular opening. When the lens stop driver 68 is subsequentlyde-energized, the lens stop member 66 is restored to the initialposition by a spring provided on a solenoid plunger core, thus providingthe open-diameter aperture again.

[0070] When the shutter driver 69 is not driven by the shutter driversource 16 (see FIG. 1), the two leaves of the shutter member 67 areconcealed inside the base member 65. When the shutter driver 69 isdriven, the shutter lever 72 is caused to undergo revolution to causethe two shutter member leaves to block the light path. When the shutterdriver 69 is subsequently de-energized, like the lens stop member 66,the shutter member 67 is retreated into the base member 65.

[0071]FIGS. 4 and 5 are timing charts illustrating an essential part ofthe imaging operation in the first embodiment of the imaging apparatus.The Figures show the vertical sync signal VD, the transfer gate pulsetrain TG, the sub-pulse train SUB, the vertical shift register shiftpulse train VT, the clamp pulse train CLP, the operation of the lensstop driver 22, the operation of the lens stop means 20, the operationof the shutter means 12 and the CCD signal as signal read out from theCCD 13 as described before regarding the functions in connection withFIG. 17. Here, the difference from the operation in the case of FIG. 18will be mainly described.

[0072] In this embodiment, unnecessary charge in the CCD 13 is swept outby fast sweep-out in the period V4 subsequent to the generation of arecording trigger signal upon the turning-“on” of the 2RSW switch 26 bafter the turning-“on” of the 1RSW switch 26 a, with or withoutconcurrent scene flux stopping executed by driving the lens stop means20 with the lens stop driver 22. In the case of stopping the scene flux,the signal generator 17 is caused to continuously output vertical shiftregister shift pulses VT at sweep-out frequency f2 (see FIG. 4). Whenthe scene flux is not stopped, that is, when the signal charge isaccumulated in the open-diameter aperture state without driving the lensstop means 20, the signal generator 17 is caused to continuously outputvertical shift register shift pulses VT at sweep-out frequency f1(f1>f2) (see FIG. 5). In FIG. 4, the response characteristic of the lensstop means 20 is not shown.

[0073] As shown, the signal generator 17 selectively provides thesweep-out frequency f for sweeping out unnecessary charge in the CCD 13;specifically, when the lens stop means 20 is driven for stopping thescene light flux, the fast sweep-out of unnecessary charge is executedat the sweep-out frequency f2 lower than the sweep-out frequency f1which is set in the case when the lens stop means 20 is not driven. Withthe setting of the sweep-out frequency f2, the consumed power in thefast sweep-out operation time section can be reduced compared to thecase of the sweep-out frequency f1. Thus, the overall peak consumedcurrent during the fast sweep-out time section with the lens stop means20 in the driven state, can be reduced substantially down to the samelevel as the consumed current in the sweep-out operation at thesweep-out frequency f1. It is thus possible to reduce the peak consumedcurrent in the entire imaging apparatus, effectively permit consumedpower reduction and battery life extension and effectively prevent thesystem stoppage by making the battery check.

[0074] A second embodiment of the present invention will now bedescribed, which again uses the construction as shown in FIG. 1. In thisembodiment, as the mode of reading out signal charge from the CCD 13with the signal generator 17, in addition to the full pixel read-outmode, in which signal charge in the 1-st to the L-th (i.e., last) lineof the CCD 13 is progressively read out as effective charge as describedbefore, a k-line read-out mode can be set. Specifically, as shown inFIG. 6, a vertically continuous central k-line area of the lightincidence surface from the (j+1)-th to the (j+k)-th line, is set as aneffective area, while setting the remaining areas from the 1-st to thej-th line and from the (j+k+1)-th to the L-th line as sweep-out areas.In this mode, the signal charge is read out from the effective areapixels, while sweeping out charge in the sweep-out area pixels asunnecessary charge by the fast sweep-out. The CPU 18 selects theseread-out modes in accordance with the operation of the 1RSW and 2RSWswitches 26 a and 26 b for controlling the operation of reading outsignal charge from the CCD 13.

[0075] Specifically, as shown in the timing chart of FIG. 7, upongeneration of the first trigger pulse with the turning-“on” of the 1RSWswitch 26 a, the operation is started by selecting the k-line read-outmode. In this mode, a sweep-out operation of sweeping out unnecessarycharge from the sweep-out area pixels in the CCD 13 by the fastsweep-out at the sweep-out frequency f1 and a read-out operation ofreading out effective charge from the pixels in the central continuousk-line effective area, are caused in synchronism to each period of thevertical sync signal VD. The k-line image data which is obtained as aresult of the read-out in the k-line read-out mode, is used for suchprocesses as auto-focusing (AF) control, auto-exposure (AE) control andauto-white-balance (AWB) control.

[0076] When the recording trigger signal is subsequently generated withthe turning-“on” of the 2RSW switch 26 b, from the next period (i.e.,period V4 in the case of FIG. 7) the full pixel read-out mode isselected. Thus, like the case of the first embodiment, unnecessarycharge in the vertical shift registers 3 (see FIG. 15) is swept outthrough the fast sweep-out by selecting the sweep-out frequency f2,lower than the sweep-out frequency f1, when the lens stop means 20 isdriven while selecting the sweep-out frequency f1 when the lens stopmeans 20 is not driven, and in the next period V5 signal charge havingbeen accumulated during the charge accumulation time section tb4 in thefast sweep-out time section is read out from all the pixels at apredetermined read-out frequency.

[0077] Thus, again in this embodiment the peak consumed current duringthe fast sweep-out time section when the lens stop means 20 is drivencan be reduced, and the same effects as obtainable with the firstembodiment can be obtained. Besides, in this embodiment, from the peridV0 in which the first trigger pulse is generated till the period V3 inwhich the recording trigger signal is generated, the k-line read-outmode is selected to read out signal charge in the centrally continuousk-line effective area, while sweeping out unnecessary charge in thepreceding and succeeding sweep-out areas by the fast sweep-out at thesweep-out frequency f1. The frame rate in these periods thus can beimproved. It is thus possible to reduce the release time lag from thefirst trigger pulse till the recording trigger signal, thus reducing thepossibility of missing a shutter chance.

[0078]FIG. 8 is a block diagram showing the construction of a thirdembodiment of the imaging apparatus according to the present invention.This embodiment is constructed by connecting a battery checker 27, whichchecks the residual capacity of a battery (not shown) (i.e., the supplyvoltage level), to the CPU 18 in the construction of the secondembodiment. In the k-line read-out mode after the first trigger pulsegeneration, the CPU 18 controls the signal generator 17 according to theoutput of the battery checker 27 to cause the signal generator 17 toselectively output vertical shift register shift pulses VT at sweep-outfrequency f1 or f2 (f1>f2) for controlling the operation of sweeping outunnecessary charge in the sweep-out areas. In the full pixel read-outmode after the recording trigger signal generation, for the unnecessarycharge sweep-out control, the CPU 18 controls the signal generator 17according to whether the light flux stop is provided by the lens stopmeans 20 as well as to the output of the battery checker 27, thuscausing the signal generator 17 to selectively output vertical shiftregister shift pulses VT at the sweep-out frequency f1 or f2. For theremainder of the construction and operations, the embodiment is the sameas the second embodiment, and here the difference in operation from thesecond embodiment will be mainly described. The battery checker 27 has afunction of checking the residual battery capacity under control of theCPU 18 and also a function of always monitoring the residual batterycapacity and, upon detection that the residual battery capacity becomeslower than a predetermined reference level (VBC0), stopping the systemby resetting the CPU 18 for preventing run-away.

[0079]FIG. 9 is a flow chart illustrating the main routine executed bythe CPU 18 in the third embodiment. The main routine is started withpower-“on” of the system. When the main routine is started, the CPU 18first executes initial setting (step S1), and then waits for theoperation of turning on the 1RSW switch 26 a (step S2).

[0080] When the CPU 18 detects in the step S2 that the 1RWS switch 26 ahas been turned on, it causes a battery check by the battery checker 27(step S3). Then the CPU 18 compares the detected supply voltage levelVcc with a predetermined first reference level VBC1 (step S4). The firstreference level VBC1 is, for instance, substantially the lower limit ofan operation voltage level range, and is set to be slightly higher thanthe above reference level VBC0, at which the CPU 18 is reset.

[0081] When the CPU 18 detects in the step S4 that Vcc<VBC1, it judgesthat the battery has been used up and can no longer be used, and sets astop mode to provide an inoperative state of itself (step S5). In thiscase, it is displayed on a liquid crystal display (not shown) or thelike that the battery can no longer be used. When the CPU 18 finds thatVcc≧VBC1, it compares the detected voltage level Vcc with apredetermined second reference level VBC2 (VBC1>VBC2) (step S6). Thesecond reference level VBC2 is set to be, for instance, substantiallythe mid voltage level in the operation guaranteeing voltage level range.

[0082] When the CPU 18 detects in the step S6 that Vcc>VBC2, it sets thesweep-out frequency f, at which to sweep out unnecessary charge in thesweep-out areas in the k-line read-out mode, to f1 (step S7). When theCPU 18 detects that VCC≦VBC2, it sets the frequency f to f2 (step S8).The CPU 18 then executes an imaging sequence in the k-line read-out modeto obtain image data for executing such processes as AF control, AEcontrol and AWB control (step S9).

[0083] Subsequently, the CPU 18 checks whether the 2RSW switch 26 b hasbeen turned on (step S10). When the CPU 18 detects that the switch is“off”, the routine goes back to the step S2 to repeat the operation asdescribed. When the CPU 18 detects that the switch has been turned on,it checks, according to the result of exposure computation in the AEcontrol executed in the step S9, whether the lens stop means 20 will beturned on (step S11).

[0084] When the CPU 18 detects in the step S11 that the lens stop means20 will be turned on, it sets the sweep-out frequency f in the fullpixel read-out mode to f2 (step S12). When the CPU 18 detects that thelens stop means 210 will be continually held “off”, it checks whetherVcc>VBC2 (step S13). When Vcc>VBC2, the CPU 18 sets the sweep-outfrequency f to f1 (step S14). When Vcc≦VBC2, the CPU 18 sets f2 (stepS12). The CPU 18 then executes the imaging sequence in the full pixelread-out mode, that is, the operation in the period V4 and followingperiods in FIG. 7 (step S15), and records the obtained image data as astill image in the recording means 21 (step S16). The routine thenreturns to the step S2.

[0085] As shown above, in this embodiment the sweep-out frequency f isselectively set to f1 or 21 in dependence on the result of the residualbattery capacity check in the battery checker 27. Specifically, when itis detected that Vcc≦VBC2, the sweep-put frequency for sweeping out thecharge in the sweep-out areas in the k-line read-out mode is set to thelower frequency f2, and also the sweep-out frequency f in the full pixelread-out mode is set to the lower frequency f2 for sweep-put controlirrespective of the operation of the lens stop means 20. Thus, inaddition to the effects obtainable in the second embodiment, theconsumed current can be reduced when the residual battery capacity isless. It is thus possible to more effectively permit the battery lifeextension and more effectively prevent the system stoppage by making thebattery check.

[0086]FIG. 10 is a block diagram showing the construction of a fourthembodiment of the imaging apparatus according to the present invention.In this embodiment, a strobo means 28 for illuminating the scene isfurther provided in connection to the CPU 18 in the construction of thethird embodiment. In the k-line read-out mode after the first triggerpulse generation, the CPU 18 controls the signal generator 17 accordingto whether the strobo means 20 is being charged as well as to the resultof check in the battery checker 27, thus causing the signal generator 17to selectively output vertical shift register shift pulses VT at thesweep-out frequency f1 or f2 (f1>f2) for controlling the operation ofsweeping out unnecessary charge in the sweep-out areas. For theunnecessary charge sweep-out operation control in the full pixelread-out mode that is set after the recording trigger signal generation,like the third embodiment, the CPU 18 controls the signal generator 17according to the lens stop means 20 is driven for stopping the scenelight flux and also to the output of the battery checker 27 to cause thesignal generator 17 to selectively output vertical shift register shiftpulses VT at the sweep-out frequency f12 to f2. For the remainder of theconstruction and the operation, this embodiment is the same as thesecond embodiment, and here the difference in operation from the thirdembodiment will be mainly described.

[0087]FIG. 11 is a flow chart illustrating the main routine executed bythe CPU 18 in the fourth embodiment. When the main routine is startedwith power-“on” of the system, the CPU 18 first executes initial setting(step S21), and waits for turning-“on” of the 1RSW switch 26 a (stepS22). When the CPU 18 detects that the 1RSW switch 26 a has been turnedon, it causes a battery check (step S23). Then the CPU 18 compares thesupply voltage level VCC and the first reference level VBC1 (step S24),and when Vcc<VBC1 it sets a stop mode of bringing about an inoperativestate of itself (step S25). When Vcc≧VBC1, the CPU 19 compares Vcc withthe second reference level VBC2 (step S26).

[0088] When the CPU 18 detects in the step S26 that Vcc>VBC2, it setsthe sweep-out frequency f for sweep-out area unnecessary charge sweepingin the k-line read-out mode to f1 (step S27). When Vcc≦VBC2, the CPU 18sets f2 (step S28). Then, the CPU 18 checks whether the strobo means 28is being charged (step S29). When the strobo means 28 is being charged,the CPU 18 sets the sweep-out frequency f to f1 irrespective of whetherthis frequency f1 has been set in the step S27 (step S30). When thestrobo means 28 is not being charged, the CPU 18 executes an imagingsequence in the k-line read-out mode at the sweep-out frequency f set inthe step S27 or S28 to obtain image data used for such processes as AFcontrol, AE control and AWB control (step S31).

[0089] In subsequent steps S32 to S38, the CPU 18 executes the sameprocesses as in the steps S10 to S16 in the third embodiment shown inFIG. 9, and records a still image in the recording means 21. The routinethen returns to the step S22.

[0090] As shown, in this embodiment, during the charging of the strobomeans 20 the sweep-out area unnecessary charge sweep-out frequency f inthe k-line read-out mode is set to f2 lower than f1. Thus, like theprevious embodiments the peak consumed current in the entire system canbe reduced, thus effectively permitting power consumption reduction andbattery life extension and more effectively preventing the systemstoppage by the battery check.

[0091]FIG. 12 is a block diagram showing the construction of a fifthembodiment of the imaging apparatus according to the present invention.In this embodiment, a temperature sensor 29 for detecting the ambienttemperature Ta is further provided in connection to the CPU 18 in theconstruction of the third embodiment. The temperature sensor 29 is athermistor or the like, and is preferably disposed near the lens stopmeans 20 or the battery. In addition, the sweep-out frequency f forsweeping out unnecessary charge in the CCD 13 with the signal generator17 can be selectively set to f1, f2, f3 or f4 (f1>f2>f3>f4). In thek-line read-out mode after the first trigger pulse generation, the CPU18 controls the signal generator 17 according to the check result in thebattery checker 27 and also to the ambient temperature Ta detected bythe temperature sensor 29 to cause the signal generator 17 toselectively output vertical shift register shift pulses VT at sweep-outfrequency f1, f2 or f3 (f1>f2), thus effecting the control of thesweep-out area unnecessary charge sweep-out operation. In the full pixelread-out mode after the recording trigger signal generation, for theunnecessary charge sweep-out operation the CPU 18 controls the signalgenerator 17 according to the ambient temperature Ta detected in thetemperature sensor 29, the provision or non-provision of the scene lightflux stopping by the lens stop means 20 and the check result in thebattery checker 27 to cause the signal generator 17 to selectivelyoutput vertical shift register shift pulses VT at a selected one of thesweep-out frequencies f1 to f4. For the remainder of the constructionand the operation, this embodiment is the same as the third embodiment,and here the difference in operation from the third embodiment will bemainly described.

[0092]FIG. 13 is a flow chart illustrating a main routine executed bythe CPU 18 in the fifth embodiment. When the main routine is startedwith power-“on” of the system, the CPU 18 executes initial setting (stepS41), and waits for the turning-“on” of the 1RSW switch 26 a (step S42).Until the 1RSW switch 26 a is turned on, the CPU 18 measures the ambienttemperature Ta by reading out the output of the temperature sensor 29(step S43).

[0093] When the CPU 18 detects in the step S42 that the 1RSW switch 26 ahas been turned on, it causes a battery check (step S44), and comparesthe supply voltage level Vcc and the first reference level VBC1 (stepS45). When Vcc<VBC1, the CPU 18 sets a stop mode to bring about aninoperative state of itself (step S46). When Vcc≧Vbc1, the CPU 18compares Vcc and the second reference level VBC1 (step S47).

[0094] When the CPU 18 detects in the step S47 that Vcc>VBC2, it setsthe sweep-out area unnecessary charge sweep-out frequency f in thek-line read-put mode to f1 (step S48). When Vcc≦VBC2, the CPU 18 sets f2(step S49). The CPU 18 then compares the detected ambient temperature Taand reference temperature Tth (step S50). When Ta<Tth, the CPU 18 setsf3 as the sweep-out frequency f irrespective of the sweep-out frequencysetting in the step S48 or S49 (step S51). When Ta≧Tth, the CPU 18executes an imaging sequence in the k-line read-out mode at thesweep-out frequency f that has been set in the step S48 or S49 to obtainimage data for such processes as AF control, AE control and AWB control(step S52).

[0095] Subsequently, the CPU 18 checks whether the 2RSW switch 26 b hasbeen turned on (step S53). When this switch is “off”, the CPU 18 returnsto the step S42 and repeats the operation as described. When the CPU 18detects that the switch has been turned on, it checks whether Ta<Tth(step S54). When Ta≧Tth, the CPU 18 executes steps S55 to S58, which arethe same processes as the steps S11 to S14 in the third embodiment shownin FIG. 9, that is, it sets either f1 for f2 as the unnecessary chargesweep-out frequency f in the full pixel read-out mode according towhether the lens stop means 20 will be turned on and also to theresidual battery capacity Vcc.

[0096] When the CPU 18 detects in the step S54 that Ta<Tth, it checkswhether the lens stop means 20 will be turned on (step S59). When thelens stop means 20 will not be turned on, the CPU 18 further checkswhether Vcc>VBC2 (step S60). When Vcc>VBC2, the CPU 18 sets f2 as theunnecessary charge sweep-out frequency f in the full pixel read-out mode(step S61). When Vcc≦VBC2, the CPU 18 sets f3 (step S61). When the CPU18 judges in the step S59 that the lens stop means 209 will be turnedon, it sets f4 as the sweep-out frequency f (step S63).

[0097] After selectively setting the sweep-out frequency f in the fullpixel read-out mode among the four frequencies f1 to f4 in the aboveway, the CPU 18 executes an imaging sequence in the full pixel read-outmode by using the selected sweep-out frequency (step S64), and recordsimage data thus obtained as a still image in the recording means 21(step S65). The routine then returns to the step S42.

[0098] As shown, in this embodiment, the sweep-out frequency f is set bytaking the ambient temperature Ta as well as the residual batterycapacity Vcc into considerations. Specifically, in the case of Vcc≦VBC2and also Ta<Tth resulting in battery capacity reduction, in the k-lineread-out mode the sweep-out frequency f is set to the still lowerfrequency f3 for sweeping out sweep-out area unnecessary charge by thefast sweep-out, and in the full pixel read-out side it is in dependenceon whether the lens stop means 20 will be turned on, that is, it is setto f3 when the lens stop means 20 will not be turned on and to the yetlower frequency f4 when the lens stop means will be turned on, forsweeping out unnecessary charge by the fast sweep-out. Thus, like theprevious embodiment the peak consumed current in the entire system canbe reduced to effectively permit power consumption reduction and batterylife extension and also effective prevention of the system stoppage bythe battery check.

[0099] The embodiments described above are by no means limitative, andvarious changes and modifications of the embodiments are possibleaccording to the present invention. For example, the fourth and fifthembodiments may be combined such that when Vcc≦VBC2, Ta<Tth and thestrobo means 28 is being charged, in the k-line read-out mode thesweep-out frequency f may be set to the yet lower frequency f4 forsweeping out sweep-out area unnecessary charge by the fast sweep-out.

[0100] Also, it is possible to control the sweep-out frequency by takingit into considerations whether such an access operation as writing imagedata in the recording means 21 will be executed. For example, thesweep-out frequency may be set to a lower frequency during an accessoperation than when no access operation prevails. In this way, it ispossible to effectively prevent loss of image data due to systemstoppage during writing of image data in the recording means 21.

[0101]FIG. 14 shows a further modification. In this instance, a consumedcurrent detector 30 for detecting the consumed current in the entiresystem is provided in connection to the CPU 18. According to the outputof the consumed current detector 30, the CPU 18 may detect the maximumtotal consumed current during the inoperative state of the lens stopmeans 20, store the detected current value in an internal RAM or a E²ROM(not shown) and control the sweep-out frequency f during the operationof the lens stop means 20 such that the total consumed current duringthe operation of the lens stop means 20 is less than the stored maximumcurrent value. In this way, it is possible to effectively prevent thesystem stoppage or burn-out of a fuse provided in a power supply system.Also, the consumed current detector 30 may be suitably combined with thebattery checker 27, the strobo means 28 and/or the temperature sensor 29noted above for controlling the sweep-out frequency in the k-lineread-out mode in the second to fifth embodiments such that the totalconsumed current is less than the stored maximum total consumed currentin the inoperative state of the lens stop means 20.

[0102] In the second to fifth embodiments, in the period from theinstant of generation of the first trigger pulse till the instant ofgeneration of the recording trigger signal the signal current in thecontinuous k lines of the central part of the light incidence surface ofthe CCD 13 is read out in the k-line read-out mode, the continuous klines may constitute any desired area of the light incidence surface.Furthermore, since it is sufficient if their release time lag can bereduced by improving the frame rate, it is possible to set any desiredread-out mode, such as one in which in the period from the first triggerpulse to the recording trigger signal thin-out read-out of all lines orlines in a certain area may be done or signal charge of lines read outby the thin-out read-out is read out while being suitably addedtogether.

[0103] The imaging element may not be of the inter-line CCD type havingthe vertical over-flow drain structure as described before, and thepresent invention is effectively applicable in the cases of using CCDimaging elements having different functions as well.

[0104] As has been described in the foregoing, according to the presentinvention the sweep-out frequency at which to sweep-out unnecessarycharge in the imaging element with a sweep-out means is controlled, sothat it can be set to a lower frequency. Thus, it is possible to reducethe peak consumed current in the entire system and effectively permitpower consumption reduction and battery life extension.

[0105] Changes in construction will occur to those skilled in the artand various apparently different modifications and embodiments may bemade without departing from the scope of the present invention. Thematter set forth in the foregoing description and accompanying drawingsis offered by way of illustration only. It is therefore intended thatthe foregoing description be regarded as illustrative rather thanlimiting.

What is claimed is:
 1. An imaging apparatus having an imaging elementfor accumulating signal charge corresponding to an incident scene lightflux in a photo-electric converting element section comprising: asweep-out means for sweeping out unnecessary charge in the imagingelement; and a control means for controlling the frequency of asweep-out of unnecessary charge by the sweep-out means.
 2. An imagingapparatus having an imaging element for accumulating signal chargecorresponding to an incident scene light flux in a photo-electricconverting element section comprising: a sweep-out means for sweepingout unnecessary charge in the imaging element; an operating conditionjudging means for judging operating condition of the imaging apparatus;and a control means for controlling a frequency of the sweep-out ofunnecessary charge by the sweep-out means on the basis of the output ofthe operating condition judging means.
 3. The imaging apparatusaccording to claim 2, wherein: the operating condition judging meansjudges at least one of consumed current, whether or not a mechanicallydriven part is being operated, the supply voltage level, the ambienttemperature, whether or not the lens stop means is operative, whether ornot the strobo means is being charged, and whether or not accessoperation of recording means is being performed.
 4. An imaging apparatushaving an imaging element for accumulating signal charge correspondingto an incident scene light flux in a photo-electric converting elementsection comprising: a sweep-out means for sweeping out unnecessarycharge in the imaging element; an operating condition judging means forjudging consumed current of the imaging apparatus; and a control meansfor controlling a frequency of the sweep-out of unnecessary charge bythe sweep-out means on the basis of the output of the operatingcondition judging means such that the consumed current will not exceed apredetermined value.
 5. An imaging apparatus having an imaging elementfor accumulating signal charge corresponding to an incident scene lightflux in a photo-electric converting element section comprising: asweep-out means for sweeping out unnecessary charge in the imagingelement; an operating condition judging means for judging whether or nota mechanically driven part is being operated; and a control means forsetting a lower sweep-out frequency of the sweep-out means when amechanically driven part is being operated than a mechanically drivenpart is not being operated.
 6. An imaging apparatus having an imagingelement for accumulating signal charge corresponding to an incidentscene light flux in a photo-electric converting element sectioncomprising: a sweep-out means for sweeping out unnecessary charge in theimaging element; an operating condition judging means for judging thesupply voltage level; and a control means for setting a lower sweep-outfrequency of the sweep-out means when the supply voltage level is lowerthan a predetermined voltage.
 7. An imaging apparatus having an imagingelement for accumulating signal charge corresponding to an incidentscene light flux in a photo-electric converting element sectioncomprising: a sweep-out means for sweeping out unnecessary charge in theimaging element; an operating condition judging means for judging theambient temperature; and a control means for controlling the sweep-outfrequency of the sweep-out means on the basis of the result of judgmentof the ambient temperature by the operating condition judging mean suchas to reduce the sweep-out frequency when the ambient temperature islower than a predetermined temperature.
 8. The imaging apparatusaccording to claim 7, wherein the operating condition judging means forjudging the ambient temperature is provided around the lens stop meansor the power supply.
 9. An imaging apparatus having an imaging elementfor accumulating signal charge corresponding to an incident scene lightflux in a photo-electric converting element section comprising: a lensstop means for stopping a light flux incident on the imaging element; asweep-out means for sweeping out unnecessary charge in the imagingelement; and a control means for controlling the sweep-out frequency ofthe sweep-out means such as to provide a lower sweep-out frequency whenthe lens stop means is operative than when the lens stop means isinoperative.
 10. The imaging apparatus according to claim 9, wherein:the control means reduces the sweep-out frequency of the sweep-out meanswhen the lens stop means is operative so that the consumed current atthis time is less than the maximum consumed current when the lens stopmeans is inoperative.
 11. An imaging apparatus having an imaging elementfor accumulating signal charge corresponding to an incident scene lightflux in a photo-electric converting element section comprising: a strobomeans for illuminating the scene; incident on the imaging element; asweep-out means for sweeping out unnecessary charge in the imagingelement; and a control means for setting a lower sweep-out frequency ofthe sweep-out means when the strobo means is being charged than when thestrobo means is not being charged.
 12. An imaging apparatus having animaging element for accumulating signal charge corresponding to anincident scene light flux in a photo-electric converting element sectioncomprising: a recording means for writing image data from the imagingelement; a control means for setting a lower sweep-out frequency of thesweep-out means during an access operation of the recording means towrite image data than during a non-access operation of the recordingmeans.
 13. An imaging apparatus having an imaging element foraccumulating signal charge corresponding to an incident scene light fluxin a photo-electric converting element section comprising: a sweep-outmeans for sweeping out unnecessary charge in the imaging element; anoperating condition judging means for judging predetermined plurality ofoperating conditions of the imaging apparatus; and a control means forselecting a frequency of the sweep-out of unnecessary charge by thesweep-out means among a plurality of predetermined frequencies on thebasis of the judged operating conditions.
 14. The imaging apparatusaccording to claim 13, wherein the plurality of frequencies is set onthe basis of number of the judged operating conditions